Laminin is a basement membrane-specific glycoprotein active in promoting cell adhesion, migration, proliferation, neurite outgrowth and differentiation. See Timpl, R. H. et al., J. Biol. Chem., 254:9933 (1979), Engel, J. E. et al., J. Mol. Biol. 150:97 (1981), and Kleinman, H.K. et al., J. Cell. Biochem. 27:317 (1985). Laminin exhibits numerous biological activities, including promoting the attachment, migration, growth, and differentiation of certain cells, see Graf, J. et al., Cell 48:989 (1987). Laminin is composed of 3 chains, A, B1 and B2. The three chains form a cruciform-like shape.
Malignant cells, with laminin receptors on their surfaces, bind and attach more readily to laminin than normal cells. Malignant cell invasiveness involves binding to laminin and the use of specific mechanisms including the production of proteolytic enzymes and the movement of the cells into normal tissues. This process involves the degradation of the basement membrane.
Peptides which have been shown to exhibit inhibition of tumor cell metastasis include the pentapeptide tyrosine-isoleucine-glycine-serine-arginine, as disclosed in European Patent Application Publication No. 0278781, Iwamoto, Y. et al., Science 238:1132 (1987) and Graf, J. et al., Biochemistry 26:6896 (1987). It would be desirable to discover other effective peptides capable of inhibiting tumor cell invasiveness by inhibiting cell attachment to laminin.